Thermal and rheological properties of granular waxy maize mutant starches afte β-amylase modification (original) (raw)
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Impact on molecular organization of amylopectin in starch granules upon annealing
Carbohydrate polymers, 2013
This study investigated the influence of the internal structure of amylopectin on annealing (3 h, 24 h) of starches from four different types of amylopectin . Regardless of the starch source and incubation time, annealing significantly increased the onset gelatinization temperature (To) and narrowed and deepened the amylopectin endotherm. However, the extent of the change in the melting temperature (Tm) and the enthalpy of gelatinization ( H) differed among the types. In terms of the To and Tm, starches from type 1 (oat, rye, barley, and waxy barley) showed the most significant response to annealing. The Tm of starches belonging to type 2 (waxy maize, rice, waxy rice, and sago) remained unchanged after 3 h of annealing. Type 1 and type 2 starches with the lowest gelatinization temperatures showed the greatest increase in melting temperature after annealing. However, type 3 (tapioca, mung bean, and arrowroot) and type 4 (potato, waxy potato, canna, and yam) starches were not in line with these observations. Instead, starches from type 3 and type 4 showed a pronounced increase in the H. The inter-block chain length (IB-CL) (distance between tightly branched units within a cluster) correlated positively (r = 0.93, p < 0.01) with the change in enthalpy after 24 h of annealing. These data indicate that a short IB-CL affects the optimum registration of double helices within the crystalline lamellae. The relationship between the gelatinization parameters before and after annealing suggests that type 1 and 2 starches might possess a high number of unpacked double helices (type 1 > type 2) compared to other types. Longer IB-CLs, which facilitate the parallel packing of splayed double helices, and the lengthening of double helices likely increased the H in type 3 and type 4 starches. It is concluded that annealing can be used as a probe for visualizing the organization of glucan chains (alignment of double helices/degree of perfection) within crystalline lamellae.
Amylopectin: Structural, gelatinisation and retrogradation studies
Food Chemistry, 1994
Amaranth, waxy corn, and commercial corn amylopectins were enzymically debranched and their fractions separated by gel filtration. In all cases a bimodal distribution of chain lengths was found, containing a high proportion of short chains. Amaranth, waxy corn starches and commercial corn amylopectin displayed an A-type X-ray diffraction pattern, which is characteristic of cereal starches, whereas amaranth amylopectin did not show a well-defined pattern, suggesting that the former samples have granular structure. Gelatinisation and retrogradation data, by differential scanning calorimetry, showed a good agreement between starches and amylopectins of the same source. Amaranth starch and its amylopectin presented a lower tendency to undergo these changes compared to the remaining tested materials. The temperature effect on retrogradation was more drastic for amaranth and waxy corn amylopectins.
Amylopectin starch granule lamellar structure as deduced from unit chain length data
Food Hydrocolloids, 2020
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International Journal of Biological Macromolecules, 2009
Structural, thermal and pasting diversity of starches from Indian and exotic lines of wheat was studied. Majority of the starches showed amylose content ranging between 22% and 28%. Endotherm temperatures (T o , T p and T c ) of the starches showed a range between 56-57, 60 -61 and 65.5-66.5 • C, respectively. Exotherms with T p between 87.0 and 88.2 • C were observed during cooling of heated starches, indicating the presence of amylose-lipid complexes. Exotherm temperatures were negatively correlated to swelling power. Amylopectin unit chains with different degree of polymerization (DP) were observed to be associated with pasting temperature, setback and thermal (endothermic T o , T p , and T c ) parameters. Amylopectin unit chains of DP 13-24 showed positive relationship with endothermic T o , T p and T c . Pasting temperature showed positive correlation with short chains (DP 6-12) while negative correlation with medium chain (DP 13-24) amylopectins. Setback was positively correlated to DP 16-18 and negatively to DSC amylose-lipid parameters.
Carbohydrate Polymers, 1998
Starch granules in excess water gelatinize in a predictable manner, where radial and tangential expansion displaces amylopectin units from granular rings as a gradual centrifugal process concluding at the granular surface. Amylopectin appears as ellipsoidal particles in waxy maize starch granules in excess water at ambient temperature and swell to spherical particles on heat application. During swelling, the amylopectin units in waxy starches remain aligned along granular rings prior to displacement. This transient stage is absent in amylose-containing starches, suggesting packing of amylose between amylopectin molecules interferes with intermolecular amylopectin interactions. Loss of granular crystalline order, as determined by loss of birefringence, is a result of displacement of amylopectin units from granular rings. The granular surface encloses the structural amylose and amylopectin and modulates gelatinization endothenns. Chemical modifications of starches were also shown to alter the sequence of molecular events during gelatinization to give predictable changes. 0
Rice starches. II. Structural aspects provide insight into swelling and pasting properties
Journal of Cereal Science, 2003
The influence of starch structure (absolute (AAM), free (FAM), lipid complexed (LAM) amylose contents and amylopectin chain length distribution) on swelling behaviour (swelling power (SP), close packing concentration ðC p Þ; total starch solubility ðSÞ and amylose leaching (AML) in a temperature range between 55 and 125 8C) and pasting properties (6, 8 and 10% dry matter starch) of five waxy and 10 normal (low (three), intermediate (four) and high (three) peak gelatinisation temperature) rice starches was investigated. At temperatures between 55 and 85 8C, waxy starches had higher SP than normal starches. In this temperature range, however, SP and C p of the normal starches were independent of AAM and FAM. On the contrary, at temperatures between 95 and 125 8C, SP and C p of all starches decreased and increased with AAM and FAM contents, respectively. For the normal starches, SP decreased and C p increased with LAM contents at 65 8C. For all starches, relative amounts of short amylopectin chains with degrees of polymerisation (DP) 6-9 led to increased SP and decreased C p at 55 and 65 8C. Opposite results were observed for relative amounts of longer amylopectin chains with DP 12-22. AAM and FAM contents decreased with starting gel point temperatures (6, 8 and 10% dry matter starch) of normal intermediate and high peak gelatinisation temperature starches. Peak and breakdown viscosities (6% dry matter starch) decreased, whereas setback and final viscosities (10% dry matter starch) increased with AAM and FAM contents of all investigated starches. Chains of DP 6-9 and 12-22, respectively, decreased and increased starting gel point temperatures. No significant correlations between amylopectin chain length distribution and peak, breakdown, setback and final viscosities were observed.
2014
Morphology, molecular structure, and thermal properties of potato starch granules with low to high phosphate content were studied as an effect of mild acid hydrolysis (lintnerization) to 80% solubilization at two temperatures (25 and 45 C). Light microscopy showed that the lintners contained apparently intact granules, which disintegrated into fragments upon dehydration. Transmission electron microscopy of rehydrated lintners revealed lacy networks of smaller subunits. The molecular composition of the lintners suggested that they largely consisted of remnants of crystalline lamellae. When lintnerization was performed at 45 C, the lintners contained more of branched dextrins compared to 25 C in both low and intermediate phosphate-containing samples. Highphosphate-containing starch was, however, unaffected by temperature and this was probably due to an altered amylopectin structure rather than the phosphate content.
Molecular structure of amylopectin from amaranth starch and its effect on physicochemical properties
International Journal of Biological Macromolecules, 2008
The molecular structure of amylopectin and its ,-limit dextrins from starch of 13 amaranth cultivars was determined by HPAEC-PAD after debranching. Chain length profiles of amylopectins showed bimodal distributions. The molar-based ratios of the average chain lengths of amylopectins (CL ap ) ranged from 17.41 to 18.22. The molar-based average chain lengths (CL ld ) and average B-chain lengths (BCL ld ) of ,limit dextrins varied from 7.68 to 8.05, and from 14.10 to 14.73, respectively. Correlation analysis indicated that most structural parameters were positively correlated with thermal properties with few exceptions, whereas the content of fraction fa (" " stands for molar-based chain length ratio) was negatively correlated with the thermal properties. Pasting properties of cold paste viscosity (CPV) and setback were also correlated with amylopectin structural parameters.
The roles of amylose and amylopectin in the gelation and retrogradation of starch
Carbohydrate Research, 1985
The retrogradation of starch gels has been studied by using X-ray diffraction, differential scanning calorimetry, and measurements of the shear modulus. Starch gels were considered as composites containing gelatinised granules embedded in an amylose matrix. The short-term development of gel structure and crystallinity in starch gels was found to be dominated by irreversible (T ~100") gelation and crystallisation within the amylose matrix. Long-term increases in the modulus of starch gels were linked to a reversible crystallisation, involving amylopectin, within the granules on storage. It was considered that the crystallisation resulted in an increase in the rigidity of the granules and thus enhanced their reinforcement of the amylose matrix. opaque starch-gel quickly develops, which becomes firmer on storage over several weeks',*. These changes have a profound effect on the texture, and hence accepta-*All percentages are w/w.